Debuffer champ

So I don't have all the things like abilities and what not, I was thinking we need a support that debuffs enemies or buffs allies. Like something called a curse, it/he/she curses and enemy that will be debuffed for a 3-5 secs. The passive can be something like every 2 min this champ autos someone it curses them (targets them) if they die, it gives this champ a stack of death which. Stack of death can be used to give the persons death to an ally healing and granting a 3-5 sec shield. Q can be he shoots a ball of dark magic which contains a curse, slowing enemies and debuffing them for a couple of seconds. W can be a tether to an enemy which every auto or ability cast on them does extra dmg ( its a thin skillshot, if the champ or enemy go far from the tether's range the tether will break) E can be this champ increases armor and mr on an ally for a couple of seconds. R can be this champ places a pool of dark magic (curse) all enemies standing in it, their armor reduces and mr reduces every second they stand in it. Maybe the title can be The Cursed Soul, a shadow isles champ. Not sure of the name. This is my first champ concept (not with stats and artwork) It might be bad, but I think we need a support who can debuff and buff for a couple seconds, seems interesting to me. KEEP IN MIND THIS CHAMP WILL BE VERY FRAGILE LIKE SORAKA. It may seem op. But if you can focus this champion AND IT HAS KIND OF LONG COOLDOWNS, so if he misses you go in.